Yevamos 12:2-3

Yevamos 12:2

If a woman performed chalitzah using a shoe that doesn’t belong to the man, or with a wooden sandal, or with his left shoe on his right foot, the chalitzah is valid. If she used a shoe larger than he wears but he can still walk in it, or one that is too small but it covers most of his foot, the chalitzah is valid. If she performed chalitzah at night, it is valid, but Rabbi Eliezer says that it is invalid. If she performs chalitzah on the man’s left foot, it is invalid, but Rabbi Eliezer says that it is valid.

Yevamos 12:3

If she loosened the shoe and spat but did not recite the text, the chalitzah is valid. If she recited the text and spat but did not loosen the shoe, the chalitzah is invalid. If she loosened the shoe and recited the text but did not spit, Rabbi Eliezer says the chalitzah is invalid and Rabbi Akiva says that it is valid. Rabbi Eliezer says it is invalid based on Deuteronomy 25:9, “so shall be done,” which implies that all of the actions of chalitzah are indispensable. Rabbi Akiva says that is no proof. The whole quote is “so shall be done to the man” – only the things done to him (i.e., removing the shoe) are indispensable.